An outbreak of measles in Japan and Taiwan has put thousands of people in quarantine and forced tourists to put off visits to southern Japan, media reports said.
More than 3,500 people in the southern Taiwanese city of Kaohsiung have been quarantined and are being monitored by the island's health authorities after coming into contact with infected crew of budget carrier Tigerair Taiwan, Taiwanese media reported.
Another 980 are being monitored following the discovery of an infection cluster at a major hospital in Taoyuan, just outside Taipei.
The outbreak has been traced to a 30-year-old male flight attendant with Tigerair Taiwan, said the semi-official Central News Agency.
He caught the highly contagious disease in Thailand in March and was confirmed to be infected on March 29. But by then he had infected two other cabin crew during a Tigerair Taiwan flight to the southern Japanese prefecture of Okinawa.
The latter two - a 34-year-old man and a 28-year-old woman - continued working until they fell seriously ill and were diagnosed with measles in early April, Central News Agency said.
So far, at least 22 people in Taiwan have been confirmed to have the highly contagious disease, which causes high fever and rashes.
It can be fatal for infants and toddlers, and may result in miscarriage.
The disease has since spread in Okinawa, which is a popular tourism destination among Taiwanese, and appeared to be heading north, with cases confirmed in Nagoya.
The source of the outbreak is the same person as in Taiwan - the male Tigerair Taiwan flight attendant who caught the virus in Thailand, reported Taiwanese media.
The man had flown to the prefecture for a holiday between March 17 and 19.
As of April 20, a total of 67 patients in Okinawa were confirmed to have contracted the disease, reported Japanese media. They included people who had come in contact with the tourist, as well as their family members and colleagues, the Asahi Shimbun said.
Some schools in Okinawa have cancelled classes.
The outbreak couldn't have happened at a worse time for local tourism: More than 170 people have cancelled trips to Okinawa ahead of the spring holiday season, according to public broadcaster NHK.
The prefectural government is receiving about 30 inquiries a day from people and travel agencies about where infections are rampant and how to protect against the virus, it added. The government plans to hold an emergency meeting of all its division chiefs on Monday, NHK said.
The disease has also been detected in the central city of Nagoya, where a resident who had visited Okinawa was diagnosed on April 11. A nurse at a local hospital was confirmed to be infected 10 days later.
Japan's Health Ministry is urging the public to get vaccinated ahead of the country's Golden Week travel peak next week.
In Hong Kong, the government's Centre for Health Protection said it was closely monitoring the situation, South China Morning Post reported. It urged travellers to remain vigilant, and noted that vaccination was the most effective way of preventing the disease, which has a 21-day incubation period.